I have two servos in an autonomous sail boat. One controls the rudder, the other the winch. I try to use both sparingly to minimize power consumption, and so I disconnect each unused servo through an n-MOSFET, and additionally, when neither are in use, I put the power regulator to sleep. Here's the circuit diagram:
I added the large caps based on recommendations from the interwebs to reduce "jitter," but given the fact that keeping a fixed position isn't really important here, are the caps doing anything besides effectively wasting energy? What I see when I scope the system is that when I power down the regulator, the caps discharge within a few seconds, meaning the power is wasted somewhere.
Best Answer
Typically, any feedback system requires capacitors, so that small fluctuations in the power supply due to movement of the motors do not create another unintentional feedback path. In this case, the charge lost in 1 discharge cycle of two 250uF capacitors is minuscule compared to your battery capacity: 250 uF * 5 V is about 1.25 mC, by comparison 1 mAh (where most batteries are on the order of thousands of mAh) is 3600 mC. Therefore, a typical 1000mAh battery can theoretically support many million charge and discharge cycles of your caps.
Not having capacitors may very well reduce your battery life, if small fluctuations in the power supply cause noise in your servo feedback readings and therefore cause the motors to move unnecessarily. Powering up the motor (even for a couple of milliseconds) is likely to waste magnitudes more energy than charging and discharging the caps.